Liquid crystal panel with pixel electrode pattern bent at bend point, and electronic apparatus

ABSTRACT

A liquid crystal panel includes: first and second substrates arranged to be opposite each other at a predetermined gap; a liquid crystal layer filled between the first and second substrates; alignment films; a counter electrode pattern formed on the first substrate; and a pixel electrode pattern formed on the first substrate so as to have a plurality of electrode branches, the extension direction of which is bent at one bend point provided near an upper pixel portion from the center of a pixel region, and which are connected at the end portion of at least the upper pixel portion or lower pixel portion, wherein the extension direction of a slit formed near the upper pixel portion from the bend point from among slits formed in the pixel electrode pattern crosses the alignment direction of the liquid crystal layer at an angle of 7° or larger.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/263,586, filed on Apr. 28, 2014, whichapplication is a divisional application of U.S. patent application Ser.No. 12/640,906, filed Dec. 17, 2009, which application claims priorityto Japanese Priority Patent Application JP 2008-324781 filed in theJapan Patent Office on Dec. 19, 2008, the entire contents of which ishereby incorporated by reference.

BACKGROUND

The present application relates to a transverse electric field drivingliquid crystal panel which performs rotation control of the arrangementof liquid crystal molecules in parallel to a substrate surface by atransverse electric field generated between a pixel electrode and acounter electrode. The present application also relates to an electronicapparatus having the liquid crystal panel mounted therein.

Description of the Related Art

At present, liquid crystal panels have various panel structuresincluding a vertical electric field display type in which an electricfield is generated in the vertical direction with respect to the panelsurface. For example, a transverse electric field display type panelstructure is suggested in which an electric field is generated in thehorizontal direction with respect to the panel surface.

In the transverse electric field display type liquid crystal panel, therotation direction of liquid crystal molecules is parallel to thesubstrate surface. That is, in the transverse electric field displaytype liquid crystal panel, there is little rotation of the liquidcrystal molecules in the vertical direction with respect to thesubstrate surface. For this reason, changes in the opticalcharacteristics (contrast, luminance, and color tone) are comparativelysmall. That is, the transverse electric field display type liquidcrystal panel has a wider viewing angle than the vertical electric fielddisplay type liquid crystal panel.

FIG. 1 shows an example of the sectional structure of a pixel regionconstituting a transverse electric field display type liquid crystalpanel. FIG. 2 shows an example of the corresponding planar structure.

A liquid crystal panel 1 has two glass substrates 3 and 5, and a liquidcrystal layer 7 filled so as to be sandwiched with the glass substrates3 and 5. A polarizing plate 9 is disposed on the outer surface of eachsubstrate, and an alignment film 11 is disposed on the inner surface ofeach substrate. Note that the alignment film 11 is used to arrange agroup of liquid crystal molecules of the liquid crystal layer 7 in apredetermined direction. In general, a polyimide film is used.

On the glass substrate 5, a pixel electrode 13 and a counter electrode15 are formed of a transparent conductive film. Of these, the pixelelectrode 13 is structured such that both ends of five comb-shapedelectrode branches 13A are respectively connected by connection portions13B. Meanwhile, the counter electrode 15 is formed below the electrodebranches 13A (near the glass substrate 5) so as to cover the entirepixel region. This electrode structure causes a parabolic electric fieldbetween the electrode branches 13A and the counter electrode 15. In FIG.1, this electric field is indicated by a broken-line arrow.

The pixel region corresponds to a region surrounded by signal lines 21and scanning lines 23 shown in FIG. 2. In each pixel region, a thin filmtransistor for controlling the application of a signal potential to thepixel electrode 13 is disposed. The gate electrode of the thin filmtransistor is connected to a scanning line 23, so the thin filmtransistor is turned on/off by the potential of the scanning line 23.

One main electrode of the thin film transistor is connected to a signalline 21 through an interconnect pattern (not shown), and the other mainelectrode of the thin film transistor is connected to a contact 25 ofthe pixel electrode. Thus, when the thin film transistor is turned on,the signal line 21 and the pixel electrode 13 are connected to eachother, and the signal potential is applied to the pixel electrode 13.

As shown in FIG. 2, in this specification, a gap between the electrodebranches 13A is called a slit 31. In FIG. 2, the extension direction ofthe slit 31 is identical to the extension direction of the signal line21.

For reference, FIGS. 3A and 3B show the sectional structure around thecontact 25.

JP-A-10-123482 and JP-A-11-202356 are examples of the related art.

SUMMARY

In the transverse electric field display type liquid crystal panel, itis known that, as shown in FIG. 4, the alignment of the liquid crystalmolecules is likely to be disturbed at both ends of the slit 31 (aroundthe connection portion of the electrode branches 13A and the connectionportion 13B). This phenomenon is called disclination. In FIG. 4, regions41 where the arrangement of the liquid crystal molecules is disturbeddue to occurrence of disclination are shaded. In FIG. 4, the alignmentof the liquid crystal molecules is disturbed at ten regions 41 in total.

If external pressure (finger press or the like) is applied to thedisclination, the disturbance of the arrangement of the liquid crystalmolecules is expanded along the extension direction of the electrodebranches 13A. Further, the disclination expanded from the upper portionof the pixel and the disclination expanded from the lower portion of thepixel are linked at the center of the pixel, and the shape ismaintained. Note that the liquid crystal molecules in the disclinationrotate in a direction opposite to the direction determined according tothe electric field direction. This phenomenon is called a reverse twistphenomenon.

FIG. 5 shows an example of the occurrence of a reverse twist phenomenon.In FIG. 5, regions 43 where the arrangement of the liquid crystalmolecules is disturbed are shaded. These regions extend along theextension direction of the electrode branches 13A.

In the case of the liquid crystal panel being used at present, if thereverse twist phenomenon occurs, the original state is not restoredafter it has been left uncontrolled. This is because the disclinationexpanded from the upper portion of the pixel is linked with thedisclination expanded from the lower portion of the pixel at the centralportion of the pixel to form a stabilized state, and the alignmentdirection of the liquid crystal molecules in the regions 43 is notrestored to the original state. As a result, the regions 43 where thereverse twist phenomenon occurs may be continuously viewed as residualimages (that is, display irregularity). Hereinafter, a residual image iscalled a reverse twist line.

An embodiment of the application provides a liquid crystal panel. Theliquid crystal panel includes first and second substrates arranged to beopposite each other at a predetermined gap, a liquid crystal layerfilled between the first and second substrates, alignment films, acounter electrode pattern formed on the first substrate, and a pixelelectrode pattern formed on the first substrate so as to have aplurality of electrode branches, the extension direction of which isbent at one bend point provided near an upper pixel portion from thecenter of a pixel region, and which are connected at the end portion ofat least the upper pixel portion.

The extension direction of a slit formed near the upper pixel portionfrom the bend point from among slits formed in the pixel electrodepattern may cross the alignment direction of the liquid crystal layer atan angle of 7° or larger. With this configuration, alignment disturbancewhich occurs in the vicinity of the upper pixel portion can besuppressed.

The extension direction of a slit formed on the side opposite to theupper pixel portion from the bend point may cross the alignmentdirection of the liquid crystal layer at an angle of 7° or larger. Withthis configuration, even though a reverse twist line grows beyond a bentregion and reaches the center of the screen, alignment disturbance canrapidly disappear.

The cross angle between the extension direction of the slit and thealignment direction of the liquid crystal layer may be equal to orlarger than 7° and equal to or smaller than 15°. This is because as thecross angle is larger, the alignment stability during voltageapplication increases, and as the cross angle is larger, transmittanceis lowered.

The pixel electrode pattern and the counter electrode pattern may beformed on the same layer surface, or may be formed on different layersurfaces. That is, if the liquid crystal panel is a transverse electricfield display type liquid crystal panel, and the pixel electrode has aslit, the sectional structure of the pixel region is not limited.

A plurality of bend points may be provided in the pixel electrodepattern. For example, when two bend points are provided, a second bendpoint may be provided around a connection portion in a lower pixelportion. This is because disclination occurs in an end portion of thelower pixel portion.

When three bend points are provided, a third bend point may be providedaround the center of the pixel region. If the third bend point isprovided, the pixel region can be divided into two regions, and aviewing angle can be widened.

When five bend points are provided, fourth and fifth bend points may beprovided around both sides of the third bend point. In this case, if thecross angle between the extension direction of a slit formed between thefourth and fifth bend points on both sides of the third bend point andthe alignment direction of the liquid crystal layer is larger than 7°,the alignment stability around the center of the pixel region duringvoltage application pixel region can be increased.

The inventors have focused on the slit end portion where disclinationoccurs. From this viewpoint, the pixel electrode pattern or thealignment film is formed such that cross angle between the slitextension direction around the relevant region and the alignmentdirection of the liquid crystal layer is equal to or larger than 7°.

With this pixel structure, the alignment stability in the slit endportion can be intensively increased.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram illustrating an example of the sectional structureof a transverse electric field display type liquid crystal panel.

FIG. 2 is a diagram illustrating an example of the planar structure of atransverse electric field display type liquid crystal panel.

FIGS. 3A and 3B are diagrams showing an example of the sectionalstructure around a contact.

FIG. 4 is a diagram illustrating disclination.

FIG. 5 is a diagram illustrating a reverse twist phenomenon.

FIG. 6 is a diagram showing an appearance example of a liquid crystalpanel module.

FIG. 7 is a diagram showing an example of the system configuration of aliquid crystal panel module.

FIG. 8 is a diagram illustrating the cross angle between the extensiondirection of each slit and the alignment direction of a liquid crystallayer.

FIG. 9 is a diagram illustrating the relationship between the magnitudeof a cross angle and display irregularity disappearance time.

FIG. 10 is a diagram illustrating the relationship between the magnitudeof a cross angle and the level of display irregularity.

FIG. 11 is a diagram illustrating the relationship between the magnitudeof a cross angle and relative transmittance.

FIG. 12 is a diagram illustrating the cross angle between the extensiondirection of a slit and the alignment direction of a liquid crystallayer when a bent region is provided in a portion of a pixel region.

FIG. 13 is a diagram illustrating the cross angle between the extensiondirection of a slit and the alignment direction of a liquid crystallayer when a bent region is provided in a portion of a pixel region.

FIG. 14 is a diagram illustrating the relationship between the arearatio of a bent region and relative transmittance according to themagnitude of a cross angle.

FIG. 15 is a diagram showing a pixel structure example when the arearatio of a bent region is 100%.

FIG. 16 is a diagram showing a first pixel structure example (planarstructure).

FIG. 17 is a diagram showing a second pixel structure example (planarstructure).

FIG. 18 is a diagram showing a third pixel structure example (planarstructure).

FIG. 19 is a diagram showing a fourth pixel structure example (planarstructure).

FIG. 20 is a diagram showing a fifth pixel structure example (planarstructure).

FIG. 21 is a diagram showing a sixth pixel structure example (planarstructure).

FIG. 22 is a diagram showing a seventh pixel structure example (planarstructure).

FIG. 23 is a diagram showing an eighth pixel structure example (planarstructure).

FIG. 24 is a diagram showing a ninth pixel structure example (sectionalstructure).

FIG. 25 is a diagram illustrating the system configuration of anelectronic apparatus.

FIG. 26 is a diagram showing an appearance example of an electronicapparatus.

FIGS. 27A and 27B are diagrams showing an appearance example of anelectronic apparatus.

FIG. 28 is a diagram showing an appearance example of an electronicapparatus.

FIGS. 29A and 29B are diagrams showing an appearance example of anelectronic apparatus.

FIG. 30 is a diagram showing an appearance example of an electronicapparatus.

DETAILED DESCRIPTION

The present application will be described below with reference to thefigures accordingly to an embodiment.

(A) Appearance Example of Liquid Crystal Panel Module and PanelStructure

(B) Characteristics Found between Extension Direction of Slit andAlignment Direction of Liquid Crystal Layer

(C) Pixel Structure Example 1 (Single Domain Structure Example with OneBend Point)

(D) Pixel Structure Example 2 (Single Domain Structure Example with OneBend Point)

(E) Pixel Structure Example 3 (Single Domain Structure Example with TwoBend Points)

(F) Pixel Structure Example 4 (Dual Domain Structure Example with ThreeBend Points)

(G) Pixel Structure Example 5 (Dual Domain Structure Example with ThreeBend Points)

(H) Pixel Structure Example 6 (Dual Domain Structure Example with FiveBend Points)

(I) Pixel Structure Example 7 (Dual Domain Structure Example with FiveBend Points)

(J) Pixel Structure Example 8 (Modification)

(K) Pixel Structure Example 9 (Modification)

(L) Pixel Structure Example 10 (Modification)

(M) Other Examples

Elements which are not provided with particular drawings or descriptionsherein are realized by existing techniques in the relevant technicalfield. Embodiments described below are exemplary, and not limiting tothe present application.

(A) Appearance Example of Liquid Crystal Panel Module and PanelStructure

FIG. 6 shows an appearance example of a liquid crystal panel module 51.The liquid crystal panel module 51 is structured such that a countersubstrate 55 is bonded to a support substrate 53. The support substrate53 is made of glass, plastic, or other substrates. The counter substrate55 is also made of glass, plastic, or other transparent substrates. Thecounter substrate 55 is a member which seals the surface of the supportsubstrate 53 with a sealant interposed therebetween.

Note that only one substrate on the light emission side may be atransparent substrate, and the other substrate may be a nontransparentsubstrate.

The liquid crystal panel 51 is provided with an FPC (Flexible PrintedCircuit) 57 for inputting an external signal or driving power, ifnecessary.

FIG. 7 shows an example of the system configuration of the liquidcrystal panel module 51. The liquid crystal panel module 51 isconfigured such that a pixel array section 63, a signal line driver 65,a gate line driver 67, and a timing controller 69 are disposed on alower glass substrate 61 (corresponding to the glass substrate 5 of FIG.1). In this embodiment, the driving circuit of the pixel array section63 is formed as a single or a plurality of semiconductor integratedcircuits, and is mounted on the glass substrate.

The pixel array section 63 has a matrix structure in which white unitseach constituting one pixel for display are arranged in M rows×Ncolumns. In this specification, the row refers to a pixel row of 3×Nsubpixels 71 arranged in the X direction of the drawing. The columnrefers to a pixel column of M subpixels 71 arranged in the Y directionof the drawing. Of course, the values M and N are determined dependingon the display resolution in the vertical direction and the displayresolution in the horizontal direction.

The signal line driver 65 is used to apply a signal potential Vsigcorresponding to a pixel gradation value to signal lines DL. In thisembodiment, the signal lines DL are arranged so as to extend in the Ydirection of the drawing.

The gate line driver 67 is used to apply control pulses for providingthe write timing of the signal potential Vsig to scanning lines WL. Inthis embodiment, the scanning lines WL are arranged so as to extend inthe X direction of the drawing.

A thin film transistor (not shown) is formed in each subpixel 71. Thethin film transistor has a gate electrode connected to a correspondingone of the scanning lines WL, one main electrode connected to acorresponding one of the signal lines DL, and the other main electrodeconnected to the pixel electrode 13 (contact 25).

The timing controller 69 is a circuit device which supplies drivingpulses to the signal line driver 65 and the gate line driver 67.

(B) Characteristics Found Between Extension Direction of Slit andAlignment Direction of Liquid Crystal Layer

As described above, in the existing pixel structure, if disturbance(reverse twist phenomenon) of the alignment of liquid crystal moleculesoccurs due to finger press or the like, the disturbance is continuouslyviewed as display irregularity.

Accordingly, the inventors have experimented on whether the disturbanceof the alignment of liquid crystal molecules can be reduced or not byitself by changing the cross angle between the extension direction ofeach slit 31 formed by the electrode branches 13A of the pixel electrode13 and the alignment direction of the liquid crystal layer 7. Thealignment direction of the liquid crystal layer 7 (also referred to as“alignment direction of liquid crystal”) is defined by the orientationof dielectric anisotropy of liquid crystal, and refers to a directionwith a large dielectric constant.

Hereinafter, the characteristics which become clear experimentally willbe described.

First, the relationship between the slit 31 and the alignment directionof the liquid crystal layer 7 will be described with reference to FIG.8. FIG. 8 is a diagram showing the planar structure of the subpixel 71.In FIG. 8, the relationship between the extension direction of the slit31 and the alignment direction of the liquid crystal layer 7 is focusedon. For this reason, a thin film transistor and the like are not shown.

The planar structure of FIG. 8 is identical to the planar structuredescribed with reference to FIG. 2, and the corresponding elements arerepresented by the same reference numerals. That is, the subpixel 71 isformed in a rectangular region surrounded by the signal lines 21extending in the Y direction and the scanning lines 23 extending in theX direction. The pixel electrode 13 has five electrode branches 13A andconnection portions 13B respectively connecting both ends of theelectrode branches 13A. In FIG. 8, the slits 31 formed between theelectrode branches 13A or the slit 31 formed between the electrodebranches 13A and the signal line 21 on the right side in the drawingextend in the Y direction.

That is, the extension direction of each slit 31 is parallel to thesignal line 21 and perpendicular to the scanning line 23.

In FIG. 8, the alignment direction of the liquid crystal layer 7 isindicated by an arrow. In FIG. 8, the oblique upper right direction withrespect to the paper is the alignment direction of the liquid crystallayer 7. In FIG. 8, the cross angle between the alignment direction ofthe liquid crystal layer 7 and the extension direction of each slit 31is indicated by α.

The inventors have focused on the cross angle α, and have measured thetime until display irregularity disappears with respect to various crossangles α.

FIG. 9 shows the measurement result. In FIG. 9, the horizontal axisrepresents the cross angle α between the extension direction of eachslit 31 and the alignment direction of the liquid crystal layer 7, andthe vertical axis represents the time until display irregularitydisappears.

From the experiment result of FIG. 9, it has been confirmed that, whenthe cross angle α is smaller than 7°, display irregularity due to thereverse twist phenomenon does not disappear by itself.

Meanwhile, when the cross angle α is equal to or larger than 7°, it hasbeen confirmed that the reverse twist line can disappear by itself. Whenthe cross angle α is 7°, the time until display irregularity disappearsis 3.5 [seconds]. Further, from the experiment result, it has beenconfirmed that, as the cross angle α becomes larger, the time untildisplay irregularity disappears is shortened. For example, when thecross angle α is 10°, it has been confirmed that display irregularitydisappears in 3 [seconds]. When the cross angle α is 15°, it has beenconfirmed that display irregularity disappears in 2.5 [seconds]. Whenthe cross angle α is 20°, it has been confirmed that displayirregularity disappears in 1.5 [seconds].

As a result, the inventors have found that, if the cross angle α betweenthe extension direction of each slit 31 and the alignment direction ofthe liquid crystal layer 7 is set to be equal to or larger than 7°, inthe transverse electric field display type liquid crystal panel, thealignment stability of liquid crystal molecules can be improved. Thatis, it has been found that, even though the reverse twist phenomenonoccurs due to finger press or the like, the disturbance of the alignmentcan disappear by itself

FIG. 10 shows the observation result regarding the relationship betweenthe cross angle α and the level of display irregularity. In FIG. 10, thehorizontal axis denotes the cross angle α between the extensiondirection of the slit 31 and the alignment direction of the liquidcrystal layer 7, and the vertical axis denotes the visible level ofdisplay irregularity.

As shown in FIG. 10, if the cross angle α is equal to or larger than10°, it has been confirmed that no display irregularity is observed evenwhen the display screen is viewed at any angle. When the cross angle αis 5°, it has been confirmed that, when the display screen is viewedfrom an oblique direction, slight display irregularity is observed. Whenthe cross angle α is equal to or larger than 5° and smaller than 10°, asshown in FIG. 10, it has been confirmed that visibility is graduallychanged.

However, it has been confirmed that, if the cross angle α is extremelylarge, the transmittance is lowered. FIG. 11 shows the confirmedtransmission characteristics. In FIG. 11, the horizontal axis denotesthe cross angle α between the extension direction of the slit 31 and thealignment direction of the liquid crystal layer 7, and the vertical axisdenotes relative transmittance. In FIG. 11, it is assumed that, when thecross angle α is 5°, the relative transmittance is 100%.

In FIG. 11, when the cross angle α is 5°, the maximum transmittance isobtained, and when the cross angle α is 45°, the minimum transmittanceis obtained. Note that, when the cross α is 45°, the relativetransmittance is about 64%.

As shown in FIG. 11, it has been seen that the cross angle α and therelative transmittance have a roughly linear relationship. From theviewpoint of transmittance, it can be seen that, as the cross angle α issmaller, better display luminance is obtained.

The characteristics shown in FIGS. 9 to 11 are obtained on theassumption that each slit 31 of the pixel electrode 12 crosses thealignment direction of the liquid crystal layer 7 at a predeterminedcross angle α over the entire pixel region, as shown in FIG. 8. In thiscase, if the cross angle α is set while placing priority on thereduction in the disappearance time of display irregularity, therelative transmittance decreases. If the cross angle α is set whileplacing priority on the relative transmittance, the disappearance timeof display irregularity increases.

Accordingly, the inventors have suggested that the cross angle α is setto be equal to or larger than 7° and equal to or smaller than 15°. Thisis because it is considered that, if the cross angle α falls within therange, the disappearance time of display irregularity and the relativetransmittance can be maintained at a satisfactory level.

Further, the inventors have experimentally confirmed the effects whenthe condition on the cross angle α is partially applied to the pixelregion. Hereinafter, the experiment result will be described.

FIGS. 12 and 13 show planar structure examples of a subpixel 71 used inthe experiment.

The planar structure shown in FIG. 12 or 13 is identical to the planarstructure described with reference to FIG. 8, and the correspondingelements are represented by the same reference numerals. That is, thesubpixel 71 is formed in a rectangular region surrounded by the signallines 21 extending in the Y direction and the scanning lines 23extending in the X direction. In FIG. 12 or 13, the pixel electrode 13has five electrode branches 13A and connection portions 13B connectingboth ends of the electrode branches 13A.

A difference from FIG. 8 is that that one bend point is provided aroundthe contact 25 for each electrode branch 13A, that is, in the upperpixel portion, and the electrode pattern of the rectangular electrodebranches 13A is bent at the bend point.

In FIG. 12 or 13, an electrode pattern is taken into consideration inwhich the electrode branches 13A near the center of the pixel regionfrom the bend point are parallel to the signal line 21, and theelectrode branches 13A near the contact 25 from the bend point areinclined in the right direction of the drawing with respect to thesignal line 21.

In FIGS. 12 and 13, the area of a bent portion (the area near thecontact 25 from the bend point) to the area of the entire pixel regionis indicated by A %. Thus, the area excluding the bent portion is(100−A) %.

In FIGS. 12 and 13, the cross angle between the extension direction ofeach slit 31 formed by the electrode branches 13A near the contact 25from the bend point and the alignment direction of the liquid crystallayer 7 is indicated by α1. Further, the cross angle between theextension direction of each slit 31 formed in parallel to the signal 21and the alignment direction of the liquid crystal layer 7 is indicatedby α2. FIG. 12 shows an example where the alignment direction is theupper right direction in the drawing and the relationship α2>α1 isestablished between the slit extension direction and the alignmentdirection of the liquid crystal layer 7. FIG. 13 shows an example wherethe alignment direction is the upper left direction in the drawing andthe relationship α1>α2 is established between the slit extensiondirection and the alignment direction of the liquid crystal layer 7.

FIG. 14 shows the experiment result. FIG. 14 shows the measurementresult of a change in the relative transmittance due to a difference inthe area ratio A (%) of the bent portion for each cross angle. In FIG.14, the horizontal axis represents the area ratio of a bent portion tothe entire pixel region, and the vertical axis represents therelationship between the cross angle and the relative transmittance. Thelines in the drawing respectively indicate the characteristics measuredfor the cross angles α1 10°, 15°, 20°, 25°, 30°, 35°, 40°, and 45°.

As shown in FIG. 14, when the area ratio A of the bent portion is 0%,the relative transmittance is 100%, regardless of the magnitude of thecross angle α1. Note that the case where the area ratio A of the bentportion is 0% refers to the pixel structure of FIG. 8.

It has been confirmed that, if the area ratio A of the bent portion islarge, the relative transmittance is lowered, regardless of themagnitude of the cross angle α1.

FIG. 15 shows an example of a pixel structure example in which the arearatio A of the bent portion is 100%. The relative transmittancecharacteristics obtained for the pixel structure shown in FIG. 15correspond to FIG. 11 described above.

Similarly to the characteristics of FIG. 11, as the cross angle α1 issmaller, the relative transmittance is higher, and as the cross angle α1is larger, the relative transmittance is lowered.

As will be seen from FIG. 14, if the portion where the electrodebranches 13A of the pixel electrode 13 are bent is limited to a portionof the pixel region, the relative transmittance of the pixel region canbe increased, as compared with the pixel structure (FIG. 15) which thebent portion is the entire pixel region.

In this case, the upper limit of the area ratio A differs depending onthe pattern structure of the pixel electrode 13 to be used or the crossangle α1 with respect to the alignment direction of the liquid crystallayer 7, but a predetermined degree of transmission should be obtained.For example, the target relative transmittance of 80% is taken intoconsideration. In FIG. 14, if the area ratio A of the bent portion isset to be 50% or smaller of the area of the pixel region, the conditionon the transmittance can be satisfied, regardless of the magnitude ofthe cross angle α1.

The lower limit of the area ratio A is set taking into consideration theresolution limit in the manufacturing process. In general, as the arearatio A is smaller, the relative transmittance is higher, regardless ofthe magnitude of the cross angle α1. Therefore, it has been consideredthat, for practical use, it is preferable to set the area ratio A to besmall in a state where the cross angle α1 is set large.

(C) Pixel Structure Example 1

The pixel structure shown in FIG. 16 is identical to the pixel structuredescribed with reference to FIG. 12 or 13 and supposes an FFS (FringeField Switching) type liquid crystal panel.

Thus, the sectional structure of the pixel region is as shown in FIG. 1.That is, the counter electrode 15 is disposed below the pixel electrode13 so as to cover the entire pixel region.

Like FIG. 12 or 13, the pixel structure shown in FIG. 16 is a pixelstructure in which one bend point is provided. The bend point isprovided around the contact 25. In FIG. 16, the area of the bent regionis enlarged for ease of understanding of the extension direction of theslit 31 extending from the bend point toward the contact 25.

In FIG. 16, the extension direction of a slit 31 formed near the centerof the pixel region from the bend point is parallel to the signal line21. The extension direction of the slit 31 extending from the bend pointtoward the contact 25 crosses the alignment direction of the liquidcrystal layer 7 at the cross angle α1 of 7° or larger. That is, FIG. 16shows a pixel structure in which the slit 31 and the alignment directioncross each other at an angle of 7° or larger only in a region around thecontact 25, and the slit 31 and the alignment direction cross each otherat an angle smaller than 7° in the remaining pixel region.

Most of reverse twist lines occur since disclination at the end portionof the slit 31 around the contact 25 grows along the slit 31 during theapplication of external pressure.

In contrast, in the pixel structure of FIG. 16, the bent region isprovided around the contact 25, so the alignment stability in the regioncan be increased. As a result, disclination growth can be suppressed.

Of course, if disclination growth is suppressed, the occurrence ofreverse twist lines is suppressed. Further, even though a reverse twistline occurs, the reverse twist line can be rapidly eliminated. In thepixel region excluding the bent region, the cross angle α2 between theslit extension direction and the alignment direction is smaller than 7°,so the relative transmittance approaches 100%.

Therefore, a liquid crystal panel with high screen luminance and a smallnumber of reverse twist lines (residual images) can be realized, ascompared with the related art.

If the area ratio A of the bent region is set to be significantly small,as shown in FIG. 14, the transmittance over the entire pixel region canbe further increased, while the effect on the alignment stability can beincreased. From the viewpoint of the balance between the alignmentregulation force and the transmittance, it is preferable that the crossangle α1 is in the range of about 7° to 15°.

(D) Pixel Structure Example 2

FIG. 17 shows a second pixel structure example. This pixel structurealso supposes an FFS (Fringe Field Switching) type liquid crystal panel.

In FIG. 17, the cross angle α2 between the extension direction of eachslit 31 formed in the pixel region excluding the bent region and thealignment direction of the liquid crystal layer 7 is equal to or largerthan 7°. The cross angle α1 between the extension direction of each slit31 formed in the bent region and the alignment direction of the liquidcrystal layer 7 is equal to or larger than the above-described crossangle α2.

In this pixel structure, the cross angle α1 between the extensiondirection of each slit 31 corresponding to the bent region and thealignment direction of the liquid crystal layer 7 can be set to be equalto or larger than 7°, so as in the pixel structure example 1, thealignment stability can be increased and disclination growth can besuppressed.

In this pixel structure, with regard to the pixel region (the centralportion of the pixel region) excluding the bent region, the extensiondirection of each slit 31 and the alignment direction of the liquidcrystal layer 7 cross each other at the angle α2 of 7° or larger. Forthis reason, even though a reverse twist line temporarily grows to theregion, the reverse twist line can disappear by itself in a short time.

As described above, with this pixel structure, a liquid crystal panelcan be realized in which the alignment stability during voltageapplication can be improved over the entire pixel region, and eventhough a reverse twist line temporarily occurs, the reverse twist linecan disappear by itself. That is, a liquid crystal panel which achieveshigher display quality than the pixel structure example 1 can berealized.

(E) Pixel Structure Example 3

FIG. 18 shows a third pixel structure example. This pixel structure alsosupposes an FFS liquid crystal panel.

This pixel structure is also identical to the above-described two pixelstructures, and corresponds to a pixel structure example with a singledomain structure. This pixel structure example has a feature that twobend points (bent regions) are provided. Specifically, a second bendpoint is provided around the connection portion 13B on the side oppositeto the contact 25.

This is to increase the alignment regulation force around both ends ofthe electrode branches 13A so as to shorten the time until a reversetwist line disappears. Of course, in this pixel structure, disclinationwhich occurs at the end portions of the electrode branches 13A on theside opposite to the contact 25 can also be suppressed.

In the pixel structure example of FIG. 18, the positions of the bendpoints and the bend directions are set to be mirror-symmetric withrespect to the center of the pixel region, but actually, the applicationis not limited thereto. For example, point-symmetry or asymmetry may beused.

Of course, if the area ratio of the bent region to the entire pixelregion increases, the transmittance is lowered, so it is preferable thatthe bent region is as small as possible. With regard to the bent region,from the viewpoint of the balance between the alignment regulation forceand the transmittance, it is preferable that the cross angle α1 is inthe range of about 7° to 15°.

(F) Pixel Structure Example 4

FIG. 19 shows a fourth pixel structure example. This pixel structurealso supposes an FFS liquid crystal panel.

In the pixel structure example of FIG. 19, a third bend point isprovided around the center of the pixel region. The pixel structure ofFIG. 19 has a vertical mirror structure from a virtual line extendingfrom the third bend point in the X-axis direction, but actually, theapplication is not limited thereto.

In the pixel structure example of FIG. 19, in the two bent regions atboth ends of the pixel region, the alignment direction of the liquidcrystal layer 7 and the extension direction of each slit 31 cross eachother at an angle of 7° or larger.

In FIG. 19, a structure in which the pixel electrode 13 has a verticalmirror structure along a virtual line extending in the X-axis directionhas been focused on, so the alignment direction of the liquid crystallayer 7 is set to be parallel to the Y-axis direction.

In the bent region at the center of the pixel region including the bendpoint 3, it is assumed that the cross angle α2 between the alignmentdirection of the liquid crystal layer 7 and the extension direction ofthe slit 31 is arbitrary. This is because the bend point 3 formed at thecenter of the pixel region is merely formed to improve the viewing angledependency first of all.

Of course, if the cross angle α2 between each slit 31 formed between thebend point 3 and the bend point 1 and the alignment direction of theliquid crystal layer 7 is equal to or larger than 7°, the alignmentstability increases. Therefore, even though a reverse twist linetemporarily occurs, the reverse twist line can be reliably eliminated.For the same reason, it is preferable that the cross angle α2 betweeneach slit 31 formed between the bend point 3 and the bend point 2 andthe alignment direction of the liquid crystal layer 7 is equal to orlarger than 7°.

In this pixel structure, the rotation direction of the liquid crystalmolecules is inverted between the upper half portion and the lower halfportion of the pixel region. That is, in the upper half portion of thepixel region in the drawing, the liquid crystal molecules rotate in thecounterclockwise direction by the application of an electric field.Meanwhile, in the lower half portion of the pixel region of the drawing,the liquid crystal molecules rotate in the clockwise direction.

As described above, the rotation direction of the liquid crystalmolecules is inverted, which compensates for the viewing angledependency in the oblique direction, so the viewing angle dependency canbe improved.

(G) Pixel Structure Example 5

FIG. 20 shows a fifth pixel structure example. This pixel structurecorresponds to a modification of the dual domain structure shown in FIG.19.

A difference is that at the third bend point, a connection branch 13Cconnecting the electrode branches 13A to each other is further provided.

In the pixel structure of FIG. 19, the rotation direction of the liquidcrystal molecules is inverted at the boundary between two upper andlower domains, and alignment disturbance is likely to occur. For thisreason, when a reverse twist line occurs, there is a significant adverseeffect on the disappearance of the reverse twist line.

Meanwhile, in the pixel structure of FIG. 20, the two domains arecompletely separated from each other by the connection branch 13C. Thus,alignment disturbance can be eliminated. As a result, with the pixelstructure shown in FIG. 20, the time until a reverse twist linedisappears can be further shortened than the pixel structure shown inFIG. 19, and display quality can be increased by as much.

(H) Pixel Structure Example 6

FIG. 21 shows a sixth pixel structure example. The pixel structure shownin FIG. 21 corresponds to a modification of the pixel structure shown inFIG. 19.

In the above-described sixth pixel structure example (FIG. 21), a methodis used in which two domains are completely separated from each other tosuppress alignment disturbance at the boundary between the domains.

Meanwhile, in this pixel structure example, a structure is used in whichfourth and fifth bend points are formed around both sides of the thirdbend point. In this case, the pixel pattern is formed such that thecross angle α3 between the extension direction of each slit 31 formedbetween the third bend point and the fourth bend point and the alignmentdirection of the liquid crystal layer 7 is equal to or larger than 7°.Similarly, the pixel pattern is formed such that the cross angle α3between the extension direction of each slit 31 formed between the thirdbend point and the fifth bend point and the alignment direction of theliquid crystal layer 7 is equal to or larger than 7°.

That is, in the sixth pixel structure example, a method is used in whichthe alignment stability increases in the region around the third bendpoint to suppress alignment disturbance at the boundary between thedomains.

Of course, the pixel structure shown in FIG. 21 is identical to thefourth pixel structure shown in FIG. 19 in that the pixel structure hasa vertical mirror structure from a virtual line extending from the thirdbend point in the X-axis direction.

That is, the extension direction of each slit in the bent regions formedaround both end portions of the pixel region crosses the alignmentdirection of the liquid crystal layer 7 at the cross angle of 7° orlarger. With this structure, the alignment stability at both endportions of the pixel region can be increased, and disclination can beeffectively suppressed.

In the region between the first bend point and the fourth bend point,the cross angle α2 between the extension direction of the correspondingslit 31 and the alignment direction of the liquid crystal layer 7 isselected so as to ensure higher transmittance. The same is applied tothe region between the second bend point and the fifth bend point.

With the above-described pixel structure, the time until disclinationoccurring at the upper and lower end portions of the pixel region anddisclination occurring at the boundary between the domains disappear canbe shortened. Further, even though reverse twist lines occurs in theseregions due to external pressure, the reverse twist lines can be rapidlyeliminated.

(I) Pixel Structure Example 7

FIG. 22 shows a seventh pixel structure example. The pixel structureshown in FIG. 22 corresponds to a modification of the pixel structureshown in FIG. 20.

In the sixth pixel structure example, the method is used in which thetwo domains are completely separated from each other to suppressalignment disturbance. However, in this pixel structure, disclinationinevitably occurs in the region around the connection branch 13C.

Accordingly, in this pixel structure example, configuration is providedsuch that fourth and fifth bend points are newly formed around bothsides of the third bend point to increase the alignment stability in theregion around the connection branch 13C. In this case, the pixel patternis formed such that the cross angle α3 between the extension directionof each slit 31 formed between the third bend point and fourth bendpoint and the alignment direction of the liquid crystal layer 7 is equalto or larger than 7°. Similarly, the pixel pattern is formed such thatthe cross angle α3 between the extension direction of each slit 31formed between the third bend point and the fifth bend point and thealignment direction of the liquid crystal layer 7 is equal to or largerthan 7°.

That is, in the seventh pixel structure example, a method is used inwhich the alignment stability in the region around the third bend pointincreases to suppress alignment disturbance.

Of course, the pixel structure shown in FIG. 22 is identical to thefifth pixel structure shown in FIG. 20 in that the pixel structure has avertical mirror structure from a virtual line extending from the thirdbend point in the X-axis direction.

That is, the extension direction of each slit in the bent regions aroundboth ends of the pixel region crosses the alignment direction of theliquid crystal layer 7 at the cross angle of 7° or larger. In theseregions, the alignment stability increases.

The extension direction of each slit between the first bend point andthe fourth bend point crosses the alignment direction of the liquidcrystal layer 7 at the cross angle α2 which is selected so as to ensurehigh transmittance. Of course, the extension direction of each slitbetween the second bend point and the fifth bend point also crosses thealignment direction of the liquid crystal layer 7 at the cross angle α2which is selected so as to ensure high transmittance.

The use of the above-described configuration makes it possible toshorten the time until disclination occurring at both end portions ofthe pixel region and disclination occurring at the boundary between thedomains disappear. The time until the reverse twist line occurring atthe central portion of the pixel region disappears can be shortened.

(J) Pixel Structure Example 8

In the above-described seven pixel structure examples, a liquid crystalpanel has been described which has a pixel structure in which thecounter electrode 15 is disposed below the comb-shaped pixel electrode13 so as to cover the entire pixel region.

Alternatively, as shown in FIG. 23, a liquid crystal panel having acomb-shaped counter electrode 15 may be adopted. In FIG. 23, theelectrode branches 15A of the counter electrode 15 are disposed so as tofill the spaces (slits 31) between the electrode branches 13A of thepixel electrode 13. That is, the electrode branches 15A of the counterelectrode 15 are disposed so as not to overlap the electrode branches13A of the pixel electrode 13 in the pixel region.

(K) Pixel Structure Example 9

In the above-described pixel structure examples, the description hasbeen made of the pixel structure in which the pixel electrode 13 and thecounter electrode 15 are formed in different layers.

Alternatively, the technique which has been suggested by the inventorsmay be applied to a transverse electric field display type liquidcrystal panel in which the pixel electrode 13 and the counter electrode15 are formed in the same layer.

FIG. 24 shows a sectional structure example corresponding to a ninthpixel structure example. The structure excluding the pixel structure 13and the counter electrode 15 is basically the same as the pixelstructure described with reference to FIGS. 1 and 2.

That is, a liquid crystal panel 91 includes two glass substrates 3 and5, and a liquid crystal layer 7 filled so as to be sandwiched with theglass substrates 3 and 5. A polarizing plate 9 is disposed on the outersurface of each substrate, and an alignment film 11 is disposed on theinner surface of each substrate.

In FIG. 24, the pixel electrode 13 and the counter electrode 15 areformed on the glass substrate 5. Of these, the pixel electrode 13 isstructured such that one ends of comb-shaped four electrode branches 13Aare connected to each other by a connection portion 13B. Meanwhile, thecounter electrode 15 is structured such that one ends of comb-shapedthree electrode branches 15A are connected to the common electrode line33. In this case, the electrode branches 15A of the counter electrode 15are disposed so as to be fitted into the spaces between the electrodebranches 13A of the pixel electrode 13. The common electrode line 33 isformed in a lattice shape so as to follow the signal lines 21 and thescanning lines 23.

For this electrode structure, as shown in FIG. 24, the electrodebranches 13A of the pixel electrode 13 and the electrode branches 15A ofthe counter electrode 15 are alternately disposed in the same layer.With this electrode structure, a parabolic electric field is generatedbetween the electrode branches 13A of the pixel electrode 13 and theelectrode branches 15A of the counter electrode 15. In FIG. 24, thiselectric field is indicated by a broken line.

With this pixel structure, a liquid crystal panel can be realized inwhich, even though the arrangement of the liquid crystal molecules isdisturbed due to the reverse twist phenomenon caused by finger press orthe like, the arrangement disturbance can be eliminated by itself inseveral seconds. Of course, a wide viewing angle according to atransverse electric field can be realized.

(L) Pixel Structure Example 10

In the above-described five pixel structure examples, a case where theextension direction of each slit 31 formed by the electrode branches 13Aof the pixel electrode 13 is parallel to the signal line 21 or crossesobliquely with respect to the signal line 21 has been described.

Alternatively, the extension direction of each slit 31 formed by theelectrode branches 13A of the pixel electrode 13 may be parallel to thescanning line 23 or may cross obliquely with respect to the scanningline 23.

(M) Other Examples

(M-1) Substrate Material

In the above description of the examples, the substrate is a glasssubstrate, but a plastic substrate or other substrates may be used.

(M-2) Product Examples

In the above description, various pixel structures capable of generatinga transverse electric field have been described. Hereinafter,description will be provided for electronic apparatuses in which aliquid crystal panel having the pixel structure according to theexamples (with no driving circuit mounted therein) or a liquid crystalpanel module (with a driving circuit mounted therein) is mounted.

FIG. 25 shows a conceptual example of the configuration of an electronicapparatus 101. The electronic apparatus 101 includes a liquid crystalpanel 103 having the above-described pixel structure, a system controlunit 105, and an operation input unit 107. The nature of processingperformed by the system control unit 105 varies depending on the producttype of the electronic apparatus 101.

The configuration of the operation input unit 107 varies depending onthe product type. A GUI (Graphic User Interface), switches, buttons, apointing device, and other operators may be used as the operation inputunit 107.

It should be noted that the electronic apparatus 101 is not limited toan apparatus designed for use in a specific field insofar as it candisplay an image or video generated inside or input from the outside.

FIG. 26 shows an appearance example of a television receiver as anelectronic apparatus. A television receiver 111 has a display screen 117on the front surface of its housing. The display screen 117 includes afront panel 113, a filter glass 115, and the like. The display screen117 corresponds to the liquid crystal panel according to the embodiment.

The electronic apparatus 101 may be, for example, a digital camera.FIGS. 27A and 27B show an appearance example of a digital camera 121.FIG. 27A shows an appearance example as viewed from the front (from thesubject), and FIG. 27B shows an appearance example when viewed from therear (from the photographer).

The digital camera 121 includes a protective cover 123, an imaging lenssection 125, a display screen 127, a control switch 129, and a shutterbutton 131. Of these, the display screen 127 corresponds to the liquidcrystal panel according to the embodiment.

The electronic apparatus 101 may be, for example, a video camcorder.FIG. 28 shows an appearance example of a video camcorder 141.

The video camcorder 141 includes an imaging lens 145 provided to thefront of a main body 143 so as to capture the image of the subject, anphotographing start/stop switch 147, and a display screen 149. Of these,the display screen 149 corresponds to the liquid crystal panel accordingto the embodiment.

The electronic apparatus 101 may be, for example, a personal digitalassistant. FIGS. 29A and 29B show an appearance example of a mobilephone 151 as a personal digital assistant. The mobile phone 151 shown inFIGS. 29A and 29B is a folder type mobile phone. FIG. 29A shows anappearance example of the mobile phone in an unfolded state, and FIG.29B shows an appearance example of the mobile phone in a folded state.

The mobile phone 151 includes an upper housing 153, a lower housing 155,a connection portion (in this example, a hinge) 157, a display screen159, an auxiliary display screen 161, a picture light 163, and animaging lens 165. Of these, the display screen 159 and the auxiliarydisplay screen 161 correspond to the liquid crystal panel according tothe embodiment.

The electronic apparatus 101 may be, for example, a computer. FIG. 30shows an appearance example of a notebook computer 171.

The notebook computer 171 includes a lower housing 173, an upper housing175, a keyboard 177, and a display screen 179. Of these, the displayscreen 179 corresponds to the liquid crystal panel according to theembodiment.

In addition to the above-described electronic apparatuses, theelectronic apparatus 101 may be, for example, a projector, an audioplayer, a game machine, an electronic book, an electronic dictionary, orthe like.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope and without diminishing itsintended advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

The application is claimed as follows:
 1. A liquid crystal panelcomprising: first and second substrates arranged to be opposite eachother at a predetermined gap; a liquid crystal layer filled between thefirst and second substrates; alignment films; a counter electrodepattern formed in a pixel region at a first substrate side, the pixelregion being surrounded by signal lines and scanning lines, the scanninglines each having an edge extending lengthwise in a first direction, thesignal lines each having an edge extending lengthwise in a seconddirection based on an overall shape of the signal lines, the seconddirection being orthogonal to the first direction; and a pixel electrodepattern formed in the pixel region at the first substrate side so as tohave a plurality of electrode branches and one or more slits betweenadjacent two branches, wherein the pixel electrode pattern includes: afirst end and a second end in the second direction; a contact hole thatis disposed adjacent to the second end and that is coupled to a thinfilm transistor; a main pixel area that is a part of the pixel electrodepattern; and a bent pixel area that is a part of the pixel electrodepattern other than the main pixel area and that is bent relative to themain pixel area at a bend line that is a line adjacent to the contacthole, the bent pixel area including the second end and the contact hole,wherein an area ratio of the bent pixel area relative to an entire areaof the pixel region is not more than 50%, wherein the pixel electrodepattern is bent at the bend line in the pixel region at an angle notless than 7 degrees relative to an alignment direction of the liquidcrystal layer, wherein the one or more slits between adjacent twobranches is/are closed at the first end and the second end, wherein eachof the slits includes: a main slit portion that is disposed in the mainpixel area and that has an edge that extends straight toward the firstend, an overall shape of at least one slit in the main slit portionextending parallel to the edge of the signal lines in the seconddirection; and a bent slit portion that is disposed in the bent pixelarea and that is a part of the slit bent at the bend line, the bent slitportion having an edge that extends toward the second end at an anglerelative to the second direction, a centerline of at least one slit inthe bent slit portion extending at an angle relative to the edge of thesignal lines in the second direction, and the bent slit portion having alength less than a length of the main slit portion, wherein thecenterline of the at least one slit in the bent slit portion extends atan angle not less than 7 degrees relative to the alignment direction ofthe liquid crystal layer.
 2. The liquid crystal panel according to claim1, wherein the pixel electrode pattern is bent at the bend line in thepixel region at an angle not more than 15 degrees relative to thealignment direction of the liquid crystal layer.
 3. The liquid crystalpanel according to claim 1, wherein the pixel electrode pattern and thecounter electrode pattern are formed on the same layer surface.
 4. Theliquid crystal panel according to claim 1, wherein the pixel electrodepattern and the counter electrode pattern are formed on different layersurfaces.
 5. The liquid crystal panel according to claim 1, wherein thepixel electrode is further bent at a second bend line in the pixelregion at an angle not less than 7 degrees relative to the alignmentdirection of the liquid crystal layer.
 6. The liquid crystal panelaccording to claim 5, wherein the pixel electrode is bent at the secondbend line in the pixel region at an angle not more than 15 degreesrelative to the alignment direction of the liquid crystal layer.
 7. Theliquid crystal panel according to claim 1, wherein the first end and thesecond end of the pixel electrode pattern overlap scanning linesdefining the pixel region with the signal lines in which the pixelelectrode pattern is bent.
 8. The liquid crystal panel according toclaim 1, wherein the counter electrode pattern is disposed below thepixel electrode pattern including the main pixel area and the bent pixelarea to cover the entire pixel region.
 9. An electronic apparatuscomprising the liquid crystal panel according to claim
 1. 10. Anelectronic apparatus comprising the liquid crystal panel according toclaim 5.